1. Technical Field
The present invention relates to liquid containers. In particular, containers designed for bulk transport of liquids by commercial transport vehicles.
2. Background Art
Transportation of liquids in bulk quantities has been implemented using a variety of methods. A common method is to use a vehicle designed solely for liquid transport. Vehicles of this type are available in both motor and rail transport forms. A disadvantage to this type of transport solution is that because the vehicle is designed for liquid cargo, it creates a backhaul problem. A backhaul is the cargo carried by the vehicle on the the probability that cargo will be carried in both directions of the trip and therefore reduces the productivity of the vehicle. In addition to the backhaul problem, the costs involved with cleaning and inspection of a vehicle designed for liquid cargo increase the cost of the cargo. For example, when the vehicle is used to carry food products, great care must be used to avoid contamination. For these reasons, it is desirable that a general purpose vehicle be provided the ability to carry liquid cargo.
Attempts have been made to use general purpose vehicles for transport of liquid cargo. One known method has been to secure a deformable liner to the inside walls of a cargo vehicle. The bottom of the liner rests on the floor of the vehicle. As the vehicle is loaded, the liquid presses the liner against the floor and walls of the vehicle. While useful for some types of cargo, this method is undesirable for food or other products which may be subject to contamination. Additionally, since the cargo is unrestrained, movement of the vehicle may cause a surging weight shift which can destabilize the Vehicle. Baffles have been used to reduce the surging problem in this type of container. However, the baffles increase the cost of the liner, increase the surface area exposed to the cargo which increases the possibility of contamination, and have a relatively limited effect on surging due to the high mass of most liquid cargos.
Shipment of bulk liquids has also been accomplished by first loading the liquids into drums and then securing the drums inside the transport vehicles. While tending to reduce the exposure to air which may contaminate some cargo, this method has proven to be unsuitable for most food items due to the remaining possibility of contamination, and the desirability of avoiding metal contact with the food items. Likewise, surging problems still exist within each drum due to the presence of air pockets in the top of the drum. A further disadvantage to this method is the high cost of using drums for shipment. Not only are the drums themselves expensive, but filling, loading and unloading are expensive labor consuming activities. In addition, as the drums are loaded onto the vehicle, they must be restrained or else the movement of the vehicle may cause the drums to be damaged or overturned in transit. The expense of using drums is further increased due to the need to provide pallets to rest the drums on during transit. The drums must be disposed of or returned. In the first instance, the cost of the pallets become part of the cost of the cargo. In the second instance, the space taken by the pallets during the return trip reduces the amount of usable cargo space.
Bag, or pillow, containers have been developed which are sealed to prevent exposure to ambient air. These containers typically have air pockets which allow surging when the vehicle is in motion. To avoid movement of this type of container, restraining straps are used to hold the bag in place. In addition to the straps, bulkheads are often required to hold the ends of the bags in place when vehicle doors are opened. Bulkheads are typically expensive and time consuming to install. An additional problem associated with bags is that when they are punctured, or if a seal breaks, an entire cargo can be lost due to drainage. Further, these bags often require inner liners when transporting food stuffs or other items requiring approval from government agencies such as the U.S. Food and Drug Administration.
A problem associated with all of the prior forms of bulk liquid containers is that they often are too expensive to use for a single delivery and then be discarded. This necessitates an expensive cleaning process prior to each use as well as the cost of storage between uses.
While addressing the basic desirability of using general purpose transport vehicles to move bulk liquid cargo, the prior art has failed to provide a single bulk transport system for liquids which is inexpensive to manufacture, has a minimum number of seals to avoid leakage, minimizes leakage in the event of a puncture or seal failure, reduces contamination due to exposure to ambient air or air pockets, and can be used without straps or other restraining devices.